Manufacture of heat exchangers via hybrid welding

Abstract

A method for forming a hybrid heat exchanger is provided. The method includes laser-texturing a metal surface to create a plurality of microstructures and subsequently melt-bonding a plastic component to the plurality of microstructures. During melt-bonding, plastic material penetrates the plurality of microstructures and conforms to the plastic component to the metal surface. After hardening inside the microstructures, the plastic component adheres to the metal surface as a hybrid component. As a result, a fastener or snap connection is not required, and the plastic-metal joint provides a barrier to water, glycol-based fluids, air, and other fluids.

The invention claimed is: 
     
       1. A method for manufacturing a heat exchanger, the method comprising:
 laser-texturing a portion of a first surface of a metal substrate to form a plurality of microstructures therein, the plurality of microstructures including a plurality of undercut channels that are spaced apart from each other along a portion thereof; 
 melt-bonding a plastic housing to the laser-textured portion of the first surface of the metal substrate, such that a molten portion of the plastic housing flows into the plurality of undercut channels defined in the metal substrate, wherein melt-bonding the plastic housing includes ultrasonically welding the plastic housing to the first surface of the metal substrate; and 
 permitting the molten portion of the plastic housing to harden while within the plurality of undercut channels, thereby joining the plastic housing to the metal substrate, wherein the plastic housing and the metal substrate define a first flow chamber for a thermal fluid, and wherein the plastic housing and the metal substrate provide a leak barrier for the thermal fluid moving through the first flow chamber, 
 wherein the plastic housing is a first plastic housing, the method further including laser-texturing a portion of a second surface of the metal substrate opposite of the first surface and ultrasonically welding a second plastic housing thereto, wherein the first and second plastic housings are joined to opposing surfaces of the metal substrate, and wherein the second plastic housing and the metal substrate define a second flow chamber for the thermal fluid. 
 
     
     
       2. The method of  claim 1  wherein laser-texturing is performed via laser ablation or continuous wave laser etching. 
     
     
       3. The method of  claim 1  wherein each of the plurality of undercut channels are formed with at least three passes of laser energy. 
     
     
       4. The method of  claim 1  wherein the plurality of undercut channels define an average depth of between 1 μm and 200 μm, inclusive. 
     
     
       5. The method of  claim 1  wherein the plurality of undercut channels define an average width of between 5 μm and 50 μm, inclusive. 
     
     
       6. The method of  claim 1  wherein the plurality of undercut channels are spaced apart from each other by between 100 μm and 400 μm, inclusive. 
     
     
       7. The method of  claim 1  wherein the plurality of undercut channels define a ratio of channel width to channel spacing of at least 1:5, the channel spacing being a distance separating adjacent ones of the plurality of channels. 
     
     
       8. The method of  claim 1  wherein the metal substrate includes aluminum, steel, copper, or alloys thereof. 
     
     
       9. The method of  claim 1  wherein the plastic housing includes polypropylene, polycarbonate, or polyamide. 
     
     
       10. The method of  claim 1  wherein the plastic housing includes a filler material dispersed within a polymer matrix. 
     
     
       11. The method of  claim 10  wherein the filler material includes glass fibers, carbon fibers, graphite fibers, carbon nanotubes, or combinations thereof.